A single carrier Discrete Fourier Transform-spread Orthogonal Frequency Division Multiplexing (DFT-SOFDM) modulation scheme has been proposed for uplink transmissions over an air interface in the 3GPP (Third Generation Partnership Project) E-UTRA (Evolved UMTS Terrestrial Radio Access) communication system. In a single carrier DFT-SOFDM communication systems, a frequency bandwidth is split into multiple contiguous frequency sub-bands, or sub-carriers, that are transmitted simultaneously. These sub-carriers are orthogonal to each other. A user may then be assigned one or more of the frequency sub-bands for an exchange of user information, thereby permitting multiple users to transmit simultaneously on the different sub-carriers. Additional sub-carriers are reserved for transmission of control signaling.
In DFT-SOFDM, uplink control signaling may be divided into two categories. A first category, data-associated control signaling, is control signaling that is always transmitted with, and used in the processing, of an uplink user data packet. Examples of this control signaling include transport format, new data indicator, and MIMO parameters. It has been proposed that all uplink transmission parameters be controlled by a Node B since it may be costly to provide reliable control information. With this approach, only the new-data indicator may need to be transmitted by a user equipment (UE) to hybrid automatic repeat request (H-ARQ). In addition, it is to be considered whether the new-data indicator is needed since an acknowledgment (ACK) may be used instead.
A second category of control signaling, that is, control signaling not associated with user data, also known as user data non-associated control signaling, is control signaling that is transmitted independently of an uplink user data packet. Examples of this control signaling include acknowledgments (ACK/NACK), Channel Quality Information (CQI), and Multiple-Input Multiple-Output (MIMO) codeword feedback. In the absence of an uplink data transmission, this control signaling is transmitted in a frequency region reserved for control signaling. In the presence of uplink data transmission, it has been proposed that this control signaling be multiplexed with data. However, no scheme has been proposed for performing such multiplexing. Furthermore, in practice, multiplexing of control signaling with uplink data is difficult due to the different performance requirements between user data and control signaling. In addition, multiplexing is made all the more difficult in that not all non-data associated control fields may be present during a user data transmission. This issue may be somewhat alleviated by scheduling user data transmissions around the non-data associated control signaling. However, this imposes restrictions on the scheduler and may not be practical in many scenarios, for example, with persistence scheduling, re-transmission with synchronous H-ARQ, and for delay sensitive services such as Voice over Internet Protocol (VoIP).
Therefore, a need exists for a method and apparatus that multiplexes user data non-associated control signaling with user data for transmission over an uplink of a single carrier DFT-SOFDM communication system.
One of ordinary skill in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of various embodiments of the present invention. Also, common and well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.